Remove in thin layer of damped plaster approx. 0.5″ to 1″ inch if thickness(water wash the surface before applying first coat). Apply the first coat of water proofing with 2 : 1 ratio with water(Wait for minimum 1 to 2 hour).

Apply second coat of water proofing with 4 : 1 ratio with water(wait for minimum 1 to 2 hour).

Similarly apply 3 coat of pure water proofing.

Finally apply 4th coat of water proofing spreading coarse sand on the coat, (confirm that after final coat surface should be opaque).

Fianally Plaster the wall in cement-sand mortar, Ensure that Plastered Wall has been cured. Finally apply three coats of water proofing for best results.